Income Taxes - Tax Effect of Significant Items Comprising the Net Deferred Tax Asset (Liability) (Details) - USD ($) $ in Thousands	Dec. 31, 2019	Dec. 31, 2018
Deferred tax asset:
Benefits from net operating loss carryforwards	$ 5,551	$ 2,518
Long-term incentive compensation plans	20,907	22,342
Investment basis differences	4,376	3,606
Depreciation and amortization	1,554	1,248
Lease liability	6,409	0
Other, primarily accrued expenses deductible when paid	3,106	3,903
Deferred tax assets, gross	41,903	33,617
Less: valuation allowance	(2,026)	(490)
Deferred tax asset	39,877	33,127
Deferred tax liability:
Intangible assets	8,013	6,852
Investment in foreign subsidiaries	2,191	1,653
Right-of-use asset	5,191	0
Other	1,672	1,758
Deferred tax liability	17,067	10,263
Net deferred tax asset	$ 22,810	$ 22,864